Processing of bristles

ABSTRACT

The invention relates to bristles, which can be used in brushes, particularly hair brushes, and to a method for producing such bristles. A method is disclosed for molding a head profile onto at least one bristle that can be used in a hair brush, wherein the at least one bristle is guided on a bristle carrier, wherein contactless heating acts upon at least the bristle head.

The invention relates to bristles, which can be used in brushes, in particular hair brushes, and to a method for producing such bristles. The invention may be used in a multitude of very different hair brushes. It is also conceivable for the bristles described herein to be used in brushes that are not used, or not primarily used to brush hair. In particular, it is also conceivable for the bristles to be used in a massage brush. Likewise, it is also conceivable for the bristles to be used in a hair care device that also heats up the hair, for example by using warm air or a warm contact surface. Corresponding devices are marketed as so-called stylers or curlers.

GB 601,371 (Denman) discloses a hair brush with non-metallic bristles. The bristles are tapered toward the tips and have a round bristle head. Denman recommends that the bristles be manufactured in a single piece with the bristle head using the injection-molding method. However, the injection-molding method has certain limitations for the shape of the bristles and it appears to be impossible to achieve a taper that does not extend to the bristle head.

The object of the present invention is to provide bristles and a method for their manufacture that is an improvement over the prior art. The bristles and brushes with the bristles are intended to have a particularly gentle effect on the hair and scalp. The manufacturing method should be suitable for mass production and should be economical with minor amounts of waste. In particular, the method should provide safe and gentle bristles and brushes to be used, even with imperfect production standards.

These objects are achieved by a method to process a bristle according to claim 1 and by a bristle according to claim 15. Preferred embodiments through which the objects are particularly well-achieved are described in the dependent claims.

Thus, what is proposed is a method to mold a head profile onto one or a multitude of bristles, in which the bristles (the plural of bristles does not exclude treatment of an individual bristle) are guided onto a bristle carrier, the bristles are vertically aligned with their longitudinal axis, and in which contactless heating acts upon at least the bristle head.

The bristle carrier can accommodate a multitude of shapes and be optimized with respect to mass production. The bristles may be held in the carrier individually or in groups of several bristles.

While a head profile is being molded, the bristles may be guided in various positions, particularly vertically. This means that the bristle head on which the profile is to be shaped should either point in a drop direction toward the top or toward the bottom. With this orientation, the effects of gravity appear to have a beneficial effect on the shape of the head. In any case, the effects of gravity do not cause any asymmetry in the shape of the head. Without wanting to present any theory regarding the method, it appears that the shape of the head profile is influenced by the forces of gravity and cohesion of the material.

The contactless heating system may be designed very different shapes. Suitable sources of heat include all suitable types of electromagnetic radiation, in particular infrared light or even microwaves. Heating can take place by means of heat radiation from a metallic object, for example from a copper block. It is conceivable for the contactless heating to come from a certain distance away, through a plane or a surface that is curved with respect to the bristles. However, it is also suitable for one or even several bristles to be guided into a heating chamber that partially surrounds the bristles. In this process, the bristle with the bristle head should normally be guided first into the heating chamber.

Suitable heating chambers can have any desired cavity shape. For round bristles, the cavity may have an at least partially cylindrical shape. Suitable heating elements include those with a series of partially or completely cylindrical cavities.

Alternatively or in addition, heating in a heating tunnel is also conceivable. Such a tunnel enables the bristles to be heated and simultaneously transported. The bristles are then transported along a longitudinal axis of the tunnel. A U-shape is well-suited for the cross-section of the tunnel (radial with respect to the longitudinal axis). To facilitate the efficiency of the method as well as to facilitate the reliable design of a suitable head profile, the dimensions of the heating chamber must be aligned with the dimensions of the bristles to be treated. In particular, the diameter of the bristles must be considered. Said diameter must be measured 5 mm below the end of the bristle head.

Radially with respect to the longitudinal axis of the bristles, the heating chamber should have a certain smallest internal diameter. This means that, when measured in any radial direction, the smallest diameter should not be less than a certain value when measured between two walls of the heating chamber. Advantageously, such smallest internal diameters are greater than the diameter of the bristles by a factor of 1-10, for example by a factor of 3-6.

Likewise, the immersion depth of the bristles into the heating chamber must also be considered. The term “immersion depth” is understood to be the bristle length that extends through a virtual plane that delineates the heating chamber in the immersion direction. A favorable immersion depth results from the bristle diameter multiplied by a factor of 0.5-10, for example by a factor of 1-4.

Furthermore, the clearance height of the bristles within the heating chamber must also be considered. The term “clearance height” is understood to be the distance from the end of the bristle head to the wall of the heating chamber, as measured in the direction from the bristle shaft to the bristle head, along the longitudinal axis of the bristles. A favorable clearance height results from the bristle diameter multiplied by a factor of 1-10, for example by a factor of 3-6.The clearance height may also be aligned to the internal diameter and then results from multiplying the internal diameter by a factor of 0.5-2, for example by a factor of 0.8-1.2.

A rotation of the bristles around their longitudinal axis can also take place in the heating chamber. For example, bristles may rotate 5-20 times around their longitudinal axis therein. This rotation of the translational motion can also be superimposed in a heating tunnel. The rotation leads to a uniform shape of the head.

The method is particularly suitable for creating spherical, pear-shaped, elliptical, or mushroom-shaped head profiles. This description assumes an idealized head profile, not including the bristle shaft extending to the head. Head profiles whose smallest axial diameter is greater than the diameter of the bristles by a factor of 1.1 to 3, for example by a factor of 1.2 to 1.8,are conceivable.

A method of the described type is conceivable in which the heating time is between 1 and 180 seconds, for example between 5 and 60 seconds, or between 10 and 30 seconds, and in which the walls of the heating chamber have a temperature of from 200 to 400° C., for example of from 250 to 350° C.

The method described can be utilized, in a particularly advantageous manner, to produce bristles that are flash-free.

It is also conceivable for a head profile to be molded on a bristle shaft blank, on both ends. Opposing heating chambers can be used to do this. The bristle shaft blank can then be separated in the center so that two bristles, each with a molded head profile, are obtained.

The invention is suitable for the molding of bristles from all common moldable materials, i.e. all suitable plastics, for example polyamides. Aliphatic polyamines are a preferred material, particularly those that are commercially available as nylon. Such aliphatic polyamides are relatively insensitive to heat, which enables the bristles to be used in a hair brush while the hair is being heated, for example by a hair dryer.

However, particularly the preferred aliphatic polyamides are known form flashes easily, because they work very well in multi-piece molding tools. Thus, if a shaped cavity is formed for a head profile in a two-piece or a multi-piece molding tool, a flash would remain during removal from the mold. Such a type of flash on the bristle head, however, damages the hair and, in addition, tends to collect soiling there. This results in a less hygienic, less gentle hairbrush.

Also conceivable in a further process step is to provide the bristles on the bristle head with a coating material. In particular, the bristle heads may be provided with a finish, for example in the form of small paint droplets that cause thickening and rounding of the bristle head.

Such painted bristle ends are well-known. However, when these types of brushes and bristles are used over longer periods, they generally cause the problem that the coating material detaches from the bristle. Therefore, it is proposed to mold a head profile to the bristle head before the coating material is applied. To this end, any modification or expansion of the bristle profile on the bristle head is conceivable that would enable improved anchoring of the coating material. For example, the end of the bristles can be designed in the form of a sphere, eclipse, mushroom, or T.

The method for producing bristles can be part of a manufacturing method for brushes. A method for producing a brush is conceivable in which the bristles are produced in a method according to any of the preceding claims, and these bristles are used with their bristle feet in a bristle carrier cushion and the bristle carrier cushion is used in a brush.

A hair brush that was produced according to any of the methods described herein may also comprise additional hair treatment devices. In particular, it is conceivable for the hair brush to also comprise an ion applicator. Such a type of ion applicator can counteract the static charging of hair. Generally, hair charges positively, which means that the application of negative ions is helpful to hair. Such an ion applicator can be line-powered or battery-powered. For a especially gentle and manageable hair brush, a battery-operated applicator is considered for the negative ions.

These and other features of the invention result from the claims as well as from the following description and/or corresponding drawings, wherein the features can form the subject matter of the invention in various combinations and sub-combinations together as well as individually, notwithstanding their inclusion in the claims. The invention is illustrated in more detail in the following by means of preferred exemplary embodiments and corresponding drawings. The drawings show the following:

FIG. 1: a schematic, perspective representation of the arrangement of bristles, bristle carrier, and heating device;

FIG. 2: a perspective representation of a suitable heating device;

FIG. 3: a perspective representation of another suitable heating device;

FIG. 4: an exemplary longitudinal section through a heating device;

FIG. 5: preferred head profiles that can be created with the disclosed method.

FIG. 1 shows a schematic view of a possible method sequence. Bristles having a bristle head (12), a bristle shaft (14), and a bristle foot (16) are held by a bristle carrier (30) in this method. The bristles (10) are placed individually on the bristle carrier (30) and are guided into the area of the heating device (40) such that the bristles (10) are subjected to the heat from the heating chamber (42). This heat affects at least the bristle heads (12) so that a head profile (20) can result there. In the method shown, the longitudinal axis of the bristles (L) is aligned vertically, i.e. in the drop direction of an object, such as would be indicated for an apple. In FIG. 1, the bristle head (12) points toward the top; however, an arrangement in which the bristle head (12) points toward the bottom is also conceivable. In such an arrangement, the bristle carrier (30) is normally above the heating device (40).

FIG. 2 shows a heating device that is suitable for the method. In said heating device, the heating cylinders (46) are provided as heating chambers (42). Bristles may be placed into the heating cylinders (46) individually or in groups, at suitable distances from one another. They remain there for a certain time period, for example between 5 and 60 seconds, or between 10 and 30 seconds. Even if they are shown otherwise for the sake of clarity, the longitudinal axis of the heating cylinders (46) is normally vertical, specifically so that the heating cylinders are open toward the bottom or so that they are open toward the top.

FIG. 3 shows a heating device (40) that can be used alternatively or in addition to the heating device shown in FIG. 2. Said heating device has a heating chamber (42) in the form of a heating tunnel (48). Said heating tunnel allows the bristle to be pulled over a certain distance. In a mass production process, it must be considered that the brushes will have to be moved translationally over a certain distance. This translational motion can be used for simultaneous heating by guiding the bristles through the heating tunnel (48). The exposure time of the bristles is, for example, between 5 and 60 seconds or between 10 and 30 seconds. A heating tunnel length that is appropriate for a certain transport rate of the bristles must be calculated from this. For example, the length of the heating tunnel may be between 0.5 and 3 meters or between 1 and 2 meters. Even when it is shown in a lying position, a heating tunnel must be aligned such that it enables the accommodation of vertical bristles in the method.

FIG. 4 shows an exemplary cross-section through a suitable heating device (40). The figure is conceivable as a cross-section through both the heating device of FIG. 3 as well as through the heating device of FIG. 2. Noticeable is a heating chamber (42) into which a bristle (10) is immersed; in this process, the bristle is vertical with the bristle head (12) at the top. The bristle shaft (14) lies primarily outside of the heating chamber, and the bristle foot (16) is held by a bristle carrier (30). The bristle has an undercut (17). This undercut (17) can advantageously be used to fix the bristle in a brush. However, this undercut (17) can also be used to hold the bristle in the bristle carrier (30) in the method described.

The virtual delineation of the heating device, as it extends as a plane over the opening of the heating chamber and beyond, is shown as a dashed line in FIG. 4. The bristle (10) has a certain immersion depth (t) in relation to this plane. This is measured between the relevant plane and the end of the bristle head (12). The internal diameter (d) can also be seen in the figure. This diameter (d) is measured radially with respect to the longitudinal axis of the bristle (L). It describes the smallest diameter that the bristle has available in the heating chamber (42).

FIG. 5 shows an example of three bristles that can be produced according to the method disclosed herein. Bristles are shown, each having a bristle shaft (14) and a bristle foot (16), which has an undercut (17). The provision of an undercut (17) is advantageous for both the production of particularly gentle brushes as well as for handling of the bristles in this method. However, the method is also well-suited for bristles with any foot shape as well as those without an undercut (17).

The first head profile shown is in the shape of the sphere. The diameter of the sphere, which is best measured in the horizontal line, is approximately double the size of the shaft diameter. The second bristle shown has an elliptical head profile (20). Its diameter axially with respect to the longitudinal axis of the bristles (da) is approximately three times as large as the diameter of the shaft. The next figure shows a mushroom-shaped head profile (20). 

1. A method to mold a head profile (20) onto at least one bristle (10) that can be used in a hair brush, in which the at least one bristle (10) is guided on a bristle carrier (30), wherein contactless heating acts upon at least the bristle head (12).
 2. The method according to claim 1, wherein the longitudinal axis of the bristles is aligned vertically.
 3. The method according to claim 2, wherein the bristle head (12) points toward the top.
 4. The method according to claim 2, wherein the bristle head (12) points toward the bottom.
 5. The method according to any of the preceding claims, wherein the contactless heating occurs in a heating chamber (42) that at least partially surrounds the at least one bristle (10).
 6. The method according to claim 5, wherein the heating chamber (42) has a smallest internal diameter, axially with respect to the longitudinal axis of the bristles, that is greater than the diameter of the bristles by a factor of 3-6.
 7. The method according to claim 5 in which the at least one bristle (10) is immersed into the heating chamber (42) and has a certain immersion depth along its longitudinal axis, and said immersion depth is greater than the diameter of the bristles by a factor of 1-4.
 8. The method according to any of the preceding claims, wherein an essentially spherical-shaped head profile (20) is produced.
 9. The method according to claim 8, wherein the diameter of the head profile (20) is greater than the diameter of the bristles by a factor of 1.1 to
 3. 10. The method according to any of the preceding claims, wherein the heating chamber (42) is formed as a heating tunnel (40), and the bristle (10) on the bristle carrier (30) is guided through the heating tunnel (48).
 11. The method according to claim 10 in which the heating tunnel (48) has a U-shaped profile.
 12. The method according to any of the preceding claims, wherein the heating time is between 10 and 30 seconds.
 13. The method according to any of the preceding claims, wherein the walls of the heating chamber (42) have a temperature of from 250 to 350° C.
 14. The method according to any of the preceding claims, wherein the bristle (10) was produced flash-free.
 15. A bristle (10) that can be used for a hair brush that was produced according to a method according to any of the preceding claims. 